[oss-security] PowerDNS Security Advisories for dnsdist 2018-08

[Remi Gacogne]

Hi all,

We just released dnsdist 1.3.3, fixing a security issue that was
reported to us, allowing a remote attacker to craft a DNS query with
trailing data such that the addition of a record by dnsdist, for example
an OPT record when adding EDNS Client Subnet, might result in the
trailing data being smuggled to the backend as a valid record while not
seen by dnsdist.

This is an issue when dnsdist is deployed as a DNS Firewall and used to
filter some records that should not be received by the backend.
This issue occurs only when either the 'useClientSubnet' or the
experimental 'addXPF' parameters are used when declaring a new backend.

The full security advisory is provided below, and can also be
found at
https://dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2018-08.html

Please feel free to contact me directly if you have any question.

Best regards,

Remi Gacogne
PowerDNS.COM BV - https://www.powerdns.com/

PowerDNS Security Advisory for dnsdist 2018-08: Record smuggling when
adding ECS or XPF
=======================================================================================

- CVE: CVE-2018-14663
- Date: November 8th 2018
- Affects: PowerDNS DNSDist up to and including 1.3.2
- Not affected: 1.3.3
- Severity: Low
- Impact: Insufficient validation
- Exploit: This problem can be triggered via crafted queries
- Risk of system compromise: No
- Solution: Upgrade to a non-affected version

An issue has been found in PowerDNS DNSDist allowing a remote attacker
to craft a DNS query with trailing data such that the addition of a
record by dnsdist, for example an OPT record when adding EDNS Client
Subnet, might result in the trailing data being smuggled to the backend
as a valid record while not seen by dnsdist.

This is an issue when dnsdist is deployed as a DNS Firewall and used to
filter some records that should not be received by the backend.

This issue occurs only when either the 'useClientSubnet' or the
experimental 'addXPF' parameters are used when declaring a new backend.

This issue has been assigned CVE-2018-14663 by Red Hat.

PowerDNS DNSDist up to and including 1.3.2 is affected.

We would like to thank Richard Gibson for finding and subsequently
reporting this issue.